I've got a bunch of clients, each using various applications, scripts, etc. and not all of those clients are necessarily "active" at any given moment. Some may be in current development, some may only get occasional updates, others dormant because the project is essentially done though they may come back for something later, and so on.
I haven't really come up with a good way to keep track of everybody's setup so that when a new WordPress security update comes around, for example, I don't have to do a mental trawl through everyone we work with to see if I need to get in touch. I was curious how others handle this. I know there are license management applications around, but they seem geared toward managing the software of your own organization.